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(11) | EP 2 339 179 A2 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Rotary compressor |
| (57) A twin hermetic rotary compressor, in which a refrigerant suction pipe (11) is connected
to a middle plate (130) interposed between a first cylinder (111) and a second cylinder
(121) to thus reduce a height of the first cylinder, and accordingly heights of a
first rolling piston (112) and a first vane can be lowered, which allows a contact
area between the first rolling piston and the first vane to be decreased so as to
reduce a refrigerant leakage from a first compression space (V1) of the first cylinder
(111), resulting in improvement of compression efficiency of the compressor.
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BACKGROUND OF THE INVENTION
1. Field of the Invention
[0001] The present invention relates to a twin rotary compressor having a plurality of compression spaces.
2. Background of the Invention
[0002] In general, refrigerant compressors are used in refrigerators or air conditioners using vapor compression refrigeration cycle (hereinafter, referred to as 'refrigeration cycle), and a constant speed type compressor which is driven at a substantially constant speed and an inverter type compressor whose rotational speed is controlled have been used.
[0003] A refrigerant compressor, in which a driving motor and a compressor operating by the driving motor are installed in an inner space of a hermetic casing, is called a hermetic compressor, and a refrigerant compressor, in which the driving motor is separately installed outside the casing, is called an open compressor. The hermetic compressors are used in most of home or commercial refrigerators. Also, the refrigerant compressors can be classified into a reciprocal type, a scroll type, a rotary type and the like according to a mechanism for compressing a refrigerant.
[0004] The rotary compressor employs a refrigerant compression mechanism using a rolling piston, which is eccentrically rotated in a compression space of a cylinder, and a vane, which partitions the compression space of the cylinder into a suction chamber and a discharge chamber.
[0005] In recent time, a twin rotary compressor, which includes a plurality of cylinders and rolling piston and vane disposed in each of the cylinders for compressing a refrigerant using a single driving motor.
[0006] The twin rotary compressors may be classified into a capacity-variable type in which a plurality of cylinders are independent of each other to independently compress a refrigerant, and a two-stage type in which a plurality of cylinders are communicated with each other to sequentially compress a refrigerant.
[0007] The twin rotary compressor may have upper and lower cylinders, which may have the same capacity or different capacities. For example, if both cylinders have the same inner diameter and the same capacity, the upper and lower cylinders have the same height. If the both cylinders have the same inner diameter cylinders have the same height. If the both cylinders have the same inner diameter and different capacities, the upper and lower cylinders have different heights.
SUMMARY OF THE INVENTION
[0008] However, in the related art twin rotary compressor, for the two-stage type rotary compressor, as a refrigerant suction pipe is connected to the lower cylinder, the lower cylinder should be formed to have a height higher than that of the upper cylinder. That is, if the refrigerant suction pipe is connected to the lower cylinder, the height of the lower cylinder should be greater than at least an outer diameter of the refrigerant suction pipe. In order for the cylinder to have a rigidity strong enough to obviate deformation thereof upon insertion of the refrigerant suction pipe, the cylinder should have a predetermined thickness in the vicinity of an inlet, in which the refrigerant suction pipe is inserted. Therefore, the overall height of the lower cylinder is required to be as thick as a value obtained by adding the outer diameter of the refrigerant suction pipe and thicknesses thereof at both upper and lower sides of the refrigerant suction pipe. However, as the height of the lower cylinder is higher, a contact area between the rolling piston and the vane in the lower cylinder is increased and accordingly a refrigerant leakage between the rolling piston and the vane is increased, thereby causing a further compressor loss.
[0009] Therefore, an aspect of the exemplary embodiment is to provide a twin rotary compressor capable of enhancing efficiency of the compressor by decreasing a refrigerant leakage out of a cylinder in view of reducing a height of the cylinder.
[0010] To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, there is provided a twin rotary compressor including a hermetic casing, a crankshaft installed in the hermetic casing and having first and second eccentric portions, a first cylinder installed in the hermetic casing and having a first rolling piston coupled to the first eccentric portion, a second cylinder installed in the hermetic casing and having a second rolling piston coupled to the second eccentric portion, an upper bearing and a lower bearing installed at one side surfaces of the first cylinder and the second cylinder, respectively, to define a first compression space and a second compression space, and a middle plate interposing between the first cylinder and the second cylinder and configured to partition the first compression space of the first cylinder and the second compression space of the second cylinder, wherein the middle plate comprises an inlet connected with a refrigerant suction pipe, the inlet is communicated with the first compression space of the first cylinder, an outlet of the first compression space of the first cylinder is connected to the second compression space of the second cylinder, and an outlet of the second compression space of the second cylinder is communicated with an inner space of the hermetic casing.
[0011] With a configuration of a twin rotary compressor according to the detailed description, as a refrigerant suction pipe is connected to a middle plate interposed between a first cylinder and a second cylinder to thus reduce a height of the first cylinder, heights of a first rolling piston and a first vane can be lowered, which allows a contact area between the first rolling piston and the first vane to be decreased so as to reduce a refrigerant leakage from a first compression space of the first cylinder, resulting in improvement of compression efficiency of the compressor.
[0012] The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention.
[0014] In the drawings:
FIG. 1 is a schematic view showing a refrigeration cycle having a two-stage type rotary compressor for sequentially compressing a refrigerant, as one type of twin rotary compressor in accordance with one exemplary embodiment;
FIGS. 2 and 3 are longitudinal views showing one exemplary embodiment of the two-stage type rotary compressor as the one type of twin rotary compressor;
FIG. 4 is a graph showing compressor efficiency according to a height of the cylinder of the two-stage rotary compressor shown in FIG. 2;
FIG. 5 is a graph showing compressor efficiency according to a ratio of a refrigerant suction pipe to a connection pipe in the two-stage type rotary compressor shown in FIG. 2; and
FIG. 6 is a longitudinal sectional view showing another exemplary embodiment of a passage for guiding first-stage compressed refrigerant to a second cylinder in the two-stage type rotary compressor shown in FIG. 2.
DETAILED DESCRIPTION OF THE INVENTION
[0015] Description will now be given in detail of a twin rotary compressor according to the exemplary embodiments, with reference to the accompanying drawings. For the sake of brief description with reference to the drawings, the same or equivalent components will be provided with the same reference numbers, and description thereof will not be repeated.
[0016] FIG. 1 is a schematic view showing a refrigeration cycle having a two-stage type rotary compressor for sequentially compressing a refrigerant, as one type of twin rotary compressor in accordance with one exemplary embodiment.
[0017] As shown in FIG. 1, a refrigeration cycle having a two-stage type rotary compressor according to one exemplary embodiment may include components, such as a compressor 1, a condenser 2, an expansion valve 3, an evaporator 4 and a phase separator 5. A refrigerant compressed in the compressor 1 is introduced into the condenser 2 to be heat-exchanged with ambient air, thereby being condensed. The condensed refrigerant becomes a low pressure refrigerant after passing through the expansion valve 3. The refrigerant flowed through the expansion valve 3 is then divided into a gas refrigerant and a liquid refrigerant by the phase separator 5. Accordingly, the liquid refrigerant is introduced into the evaporator 4 and evaporated therein through heat-exchange so as to be introduced into an accumulator 6 in a gas state. Such refrigerant then flows from the accumulator 6 into a first compression unit (not shown) of the compressor 1 via a refrigerant suction pipe 11. Also, the gas refrigerant divided by the phase separator 5 is introduced into the compressor 1 via an injection pipe 13. An intermediate pressure refrigerant compressed in the first compression unit of the compressor 1 and the refrigerant introduced via the injection pipe 13 then flow into a second compression unit (not shown) of the compressor 1 to be compressed into a high pressure refrigerant, thereby being discharged into the condenser 2 via a refrigerant discharge pipe 12.
[0018] FIGS. 2 and 3 are longitudinal views showing one exemplary embodiment of the two-stage type rotary compressor as the one type of twin rotary compressor.
[0019] As shown in FIGS. 2 and 3, in a configuration of the two-stage type rotary compressor 1 according to the one exemplary embodiment, a driving motor 102 may be installed in an inner space of the hermetic casing 101 to generate a driving force, and a first compression unit 110 and a second compression unit 120 may be disposed below the driving motor 102 with a middle plate 130 being interposed therebetween for separation such that the first compression unit 110 can define a low pressure side and the second compression unit 120 can define a high pressure side, from the lower side of the casing 101. Also, a refrigerant suction pipe 11 may be installed at a side surface of the hermetic casing 101 and inserted into the hermetic casing 101 so as to be connected to an inlet of the first compression unit 110 via the middle plate 130. A refrigerant discharge pipe 12 may be installed at a top of the hermetic casing 101. The refrigerant discharge pipe 12 may be connected to the inner space of the hermetic casing 101 so as to discharge a refrigerant into the condenser 2.
[0020] The driving motor 102 may include a stator 103 secured with an inner circumferential surface of the hermetic casing 101, a rotor 104 rotatably installed in the stator 103, and a crankshaft 105 coupled to the center of the rotor 104 to transfer a rotating force to each compression unit 1 1 0 and 120.
[0021] The stator 103 may be formed by laminating steel plates having a ring shape and winding a coil C on the laminated steel plates.
[0023] The crankshaft 105 may include a shaft portion 106 having a bar-like shape with a predetermined length and integrally fixed through a shaft center of the rotor 104, and first and second eccentric portions 107 and 108 eccentrically protruded from a lower part of the shaft portion 106 in a radial direction to be rotatably coupled to first and second rolling pistons 112 and 122, respectively, which will be explained later.
[0024] An oil passage (not shown) may be formed through from lower to upper ends of the shaft portion 106, and an oil feeder 109 may be coupled to a lower end of the oil passage.
[0025] The first eccentric portion 107 and the second eccentric portion 108 may be formed such that a suction process and a discharge process of the first compression unit 110 have a phase difference of about 180° with respect to those of the second compression unit 120. The first eccentric portion 107 and the second eccentric portion 108 may have widths and heights enough to be housed within a first cylinder 111 and a second cylinder 121, respectively, which will be explained later.
[0026] At least one of the first and second eccentric portions 107 and 108 may include a balance hole 107a or 108a for reducing a weight thereof.
[0027] The first compression unit 110 and the second compression unit 120 may be laminated, with interposing the middle plate 130 therebetween, in the order of the first compression unit 110, the middle plate 130 and the second compression unit 120 from the lower side. Alternatively, they may be laminated in the order of the second compression unit 120, the middle plate 130 and the first compression unit 110.
[0028] The first compression unit 110 may include a first cylinder 111 having a first compression space V1, a first rolling piston 112 orbitingly housed in the first cylinder 111 and rotatably coupled to the first eccentric portion 107, a first vane 113 coupled to the first cylinder 111 to be linearly movable and contacting an outer circumferential surface of the first rolling piston 112 upon being pressed, and a first vane spring 114 elastically supported at a rear side of the first vane 113.
[0029] A height H1 of the first cylinder 111 may be the same as a height H2 of the second cylinder 121. Furthermore, as the refrigerant suction pipe 11 is connected to the middle plate 130 and a connection pipe 14 to be explained later is connected to the second cylinder 121, the height H1 of the first cylinder 111 may be lower than the height H2 of the second cylinder 121.
[0030] The first cylinder 111 may include a suction port 115 formed at one edge of its inner circumferential surface to be connected to the refrigerant suction pipe 11, a first vane slot 116 formed at one side of the suction port 115 in a circumferential direction such that the first vane 113 can be slid therein, and a first discharge guide groove (not shown) formed at another side of the first vane slot 116 to be connected to a first outlet 141, which will be explained later.
[0031] The second compression unit 120 may include a second cylinder 121 having a second compression space V2, a second rolling piston 122 orbitingly housed in the second cylinder 121 and rotatably coupled to the second eccentric portion 108, a second vane 123 coupled to the second cylinder 121 to be linearly movable and contacting an outer circumferential surface of the second rolling piston 122 upon being pressed, and a second vane spring 124 elastically supported at a rear side of the second vane 123.
[0032] The second cylinder 121 may include a second inlet 125 formed at one side thereof to be connected to the first cylinder 111 via the connection pipe 14, a second vane slot 126 formed at one side of the second inlet 125 such that the second vane 123 can be slid therein, and a second discharge guide groove (not shown) formed at another side of the second vane slot 126 to be connected to a second outlet 151, which will be explained later.
[0033] The middle plate 130 may have a ring shape, and include a first inlet 131 formed at one side of its outer circumferential surface to be connected to the refrigerant suction pipe 11. The first inlet 131 may be recessed from an outer circumferential surface of the middle plate 130 by a predetermined depth. A communication hole 132 may be formed at a middle portion of the first inlet 131, or at an inner end of the first inlet 131 in an axial direction or with an inclination angle so as to be communicated with the suction port 115 of the first cylinder 111. Therefore, the middle plate 130 may preferably be formed such that the first inlet 131 has a diameter long enough to be communicated with the refrigerant suction pipe 11. Simultaneously, the middle plate 130 may preferably be formed to have a predetermined thickness in the vicinity of the first inlet 131 so as to ensure reliability thereof.
[0034] Irrespective of the order of laminating the first and second compression units 110 and 120, a lower bearing 140 and an upper bearing 150 may be installed at lower and upper sides of the laminated compression units so as to support the crankshaft 105 in an axial direction and simultaneously define the first and second compression spaces V1 and V2, respectively together with the cylinders 111 and 121.
[0035] The lower bearing 140 may include a first outlet 141 formed at one side thereof such that a refrigerant first-stage compressed in the first cylinder 111 is discharged therethrough, and a first discharge valve 142 installed at an end of the first outlet 141. A specific storage space 143 may be formed at one side surface of the lower bearing 140, namely, at a surface opposite to the bearing surface. The storage space 143 may be covered with a cover plate 144 coupled to the lower bearing 140. A communication hole 145 may be formed at one side of the storage space 143, thus to allow a refrigerant discharged into the storage space 143 to be introduced into the second cylinder 121, which will be explained later, via the connection pipe 14.
[0036] The upper bearing 150 may include a second outlet 151 formed at one side thereof to discharge a refrigerant second-stage compressed in the second cylinder 121 therethrough, and a second discharge valve 152 installed at an end of the second outlet 151. A muffler 153 for housing the second discharge valve 152 may be installed at one side surface of the upper bearing 150, namely, at a surface opposite to the bearing surface.
[0038] That is, when the rotor 104 rotates as power is supplied to the stator 103 of the driving motor 102, the crankshaft 105 rotates together with the rotor 103 so as to transfer a rotating force of the driving motor 102 to both the first and second compression units 110 and 120. The first rolling piston 112 and the first vane 113 and the second rolling piston 122 and the second vane 123, which are respectively disposed in the first and second compression units 110 and 120, perform an eccentric rotation in the first compression space V1 and the second compression space V2, respectively, thereby compressing a refrigerant with a phase difference of 180° therebetween.
[0039] For instance, when a suction process is started in the first compression space V1, the refrigerant is introduced into the first compression space V1 of the first cylinder 111 sequentially through the accumulator 6, the refrigerant suction pipe 11, the first inlet 131 and the communication hole 132 of the middle plate 130 and the suction port 115 of the first cylinder 111, thereby being first-stage compressed. The first-stage compressed refrigerant is then discharged into the storage space 143 of the lower bearing 140 via the first outlet 141.
[0040] During the compression process in the first compression space V1, a suction process is started in the second compression space V2, which has the phase difference of 180° from the first compression space V1. Accordingly, the refrigerant, which has been first-stage compressed in the first cylinder 111 and discharged into the storage space 143 of the lower bearing 140, is introduced into the second compression space V2 of the second cylinder 121 via the connection pipe 14. The refrigerant introduced in the second compression space V2 is then second-stage compressed in the second compression space V2 of the second cylinder 120, and discharged into the inner space of the hermetic casing 101 via the second outlet 151 and the muffler 153, thereby being discharged into the refrigeration cycle via the refrigerant discharge pipe 12. The series of processes are repeated.
[0041] Here, as the refrigerant suction pipe 11 is connected to the middle plate 130, the refrigerant suction pipe 11 does not have to be connected directly to the first cylinders 111, so as to reduce the height H1 of the first cylinder 111. Consequently, a contact area between the first rolling piston 112 and the first vane 113 can be reduced, which allows reduction of a refrigerant leakage from the first compression space V1, resulting in enhancing the performance of the compressor.
[0042] Referring to FIGS. 2 and 3, the connection pipe 14 is configured such that one end is connected to the communication hole 145 of the lower bearing 140 through the hermetic casing 101, and another end is inserted in the second inlet 125 of the second cylinder 121 through the hermetic casing 101 to be coupled thereto. The connection pipe 14 may have a diameter shorter than a diameter of the refrigerant suction pipe 11.
[0043] For example, to enhance the performance of the compressor, the connection pipe 14 may preferably have a diameter D1 greater than 0.5 times of a diameter D2 of the refrigerant suction pipe 11 and smaller than 0.3 times thereof. That is, as shown in FIGS. 4 and 5, if the diameter D1 of the connection pipe 14 is smaller than or equal to 0.5 times of the diameter D2 of the refrigerant suction pipe 11, the refrigerant, which is first-stage compressed in the first compression space V1 to be discharged into the storage space 143, may not flow fast toward the second compression space V2 due to flow resistance, thereby lowering the performance of the compressor. On the other hand, if the diameter D1 of the connection pipe 14 is equal to or greater than 3.0 times of the diameter D2 of the refrigerant suction pipe 11, the diameter of the connection pipe 14 increases that much. Accordingly, the height H2 of the second cylinder 121 drastically increases to cause further refrigerant leakage between the second rolling piston 122 and the second vane 123, thereby lowering the performance of the compressor.
[0044] Also, the foregoing embodiment illustrates that the height of the first cylinders 111 is lower than the height ol the second cylinder 121. Alternatively, the first and second cylinders 111 and 121 may have the same height. In this case, the diameter of the connection pipe 14 may preferably be formed to be shorter than the diameter D2 of the refrigerant suction pipe 11, so as to enhance the performance of the compressor.
[0045] In the meantime, the first an second cylinders 111 and 121, as aforesaid, may be connected to each other via the separately employed connection pipe 14, and the connection pipe 14 is connected thereto via the outside of the hermetic casing 101. Alternatively, as shown in FIG. 6, the first an second cylinders 111 and 121 may be communicated with each other via an internal passage F, which penetrates sequentially through the lower bearing 140, the first cylinder 111, the middle plate 130 and the second cylinder 121 so as to cause a refrigerant discharged into the storage space 143 to flow into the second compression space V2. In these cases, the injection pipe 13 may be connected any of the connection pipe 14 or the internal passage F, and the compression efficiency of the compressor can also be enhanced thereby. Also, even in this case, a diameter of the internal passage F may preferably be formed to be greater than 0.5 times of a diameter D2 of the refrigerant suction pipe 11 and smaller than 0.3 times thereof.
[0046] The foregoing embodiments and advantages are merely exemplary and are not to be construed as limiting the present disclosure. The present teachings can be readily applied to other types of apparatuses. This description is intended to be illustrative, and not to limit the scope of the claims. Many alternatives, modifications, and variations will be apparent to those skilled in the art. The features, structures, methods, and other characteristics of the exemplary embodiments described herein may be combined in various ways to obtain additional and/or alternative exemplary embodiments.
[0047] As the present features may be embodied in several forms without departing from the characteristics thereof, it should also be understood that the above-described embodiments are not limited by any of the details of the foregoing description, unless otherwise specified, but rather should be construed broadly within its scope as defined in the appended claims, and therefore all changes and modifications that fall within the metes and bounds of the claims, or equivalents of such metes and bounds are therefore intended to be embraced by the appended claims.
1. A twin rotary compressor comprising:
a hermetic casing (101);
a crankshaft (105) installed in the hermetic casing (101) and having first and second eccentric portions (107, 108);
a first cylinder (111) installed in the hermetic casing (101) and having a first rolling piston (112) coupled to the first eccentric portion (107);
a second cylinder (121) installed in the hermetic casing (101) and having a second rolling piston (1 22) couples to the second eccentric portion (108);
an upper bearing (150) installed at one side surface of the first cylinder (111) and a lower bearing (140) installed at one side surface of the second cylinder (121), to define a first compression space (V1) and a second compression space (V2); and
a middle plate (130) interposed between the first cylinder (111) and the second cylinder (121) and configured to partition the first compression space (V1) of the first cylinder (111) and the second compression space (V2) of the second cylinder(121),
wherein the middle plate (130) comprises an inlet (131) connected with a refrigerant suction pipe (11), the inlet (131) being in communication with the first compression space (V1) of the first cylinder (111), an outlet (141) of the first compression space (V1) of the first cylinder (111) being connected to the second compression space (V2) of the second cylinder (121), and an outlet (151) of the second compression space (V2) of the second cylinder (121) being in communication with an inner space of the hermetic casing (101).
2. The twin rotary compressor of claim 1, wherein the height of the first cylinder (111)
is lower than or equal to the height of the second cylinder (121).
3. The twin rotary compressor of claim 1 or 2, wherein the height of the second eccentric
portion (108) is lower than or equal to the height of the first eccentric portion
(107).
4. The twin rotary compressor of any one of claims 1 to 3, wherein at least one of the
first and second eccentric portions (107, 108) comprises a balance hole (107a, 1 08a)
for reducing a weight thereof.
5. The twin rotary compressor of any one of claims 1 to 4, wherein a connection pipe
(14) is connected via an outside of the hermetic casing (101) so as to guide a refrigerant
first-stage compressed in the first compression space (V1) of the first cylinder (111)
into the second compression space (V2) of the second cylinder (121).
6. The twin rotary compressor of claim 5, wherein a storage space (143) is formed at
an outlet side of the first cylinder (111) to define an intermediate pressure chamber,
wherein one end of the connection pipe (14) is connected to one side of the storage
space (143) and another end thereof is connected to a second inlet of the second cylinder
(121).
7. The twin rotary compressor of claim 6, wherein the storage space (143) is configured
such that a groove is formed at one side surface of the lower bearing (140) and the
groove is covered with a cover plate (144) coupled to the lower bearing (140).
8. The twin rotary compressor of any one of claims 1 to 4, wherein an internal passage
(F) is formed sequentially through the first cylinder (111), the middle plate (130)
and the second cylinder (121) to guide the refrigerant first-stage compressed in the
first compression space (V1) of the first cylinder (111) into the second compression
space (V2) of the second cylinder (121).
9. The twin rotary compressor of claim 8, wherein a storage space (143) is formed at
an outlet side of the first cylinder (111) to define an intermediate pressure chamber,
wherein one end of the internal passage (F) is communicated with the storage space
(143) and another end of the internal passage (F) is communicated with the second
compression space (V2) of the second cylinder (121).
10. The twin rotary compressor of any of claims 1 to 9, wherein a diameter of a refrigerant
passage (F) is formed to be greater than 0.5 times of a diameter (D2) of the refrigerant
suction pipe (11) and smaller than 3.0 times thereof.